A pack of monsters calling themselves the “Clan of the  Seafolk” arrive on the shores of City J intent on invading the land.  When the hero sent to fight them is defeated easily by the Deep Sea King  himself, Saitama and Genos head for the city to help.
               
              
                Casts: 
                Kazuhiro Yamaji, Yuichi Nakamura, Kenjiro Tsuda, Aoi Yuki, Hiroki Yasumoto, Saori Hayami, Makoto Furukawa, Kaito Ishikawa, Hikaru Midorikawa